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BEĞEN, Ali Cengiz

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Ali Cengiz

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BEĞEN
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Now showing 1 - 10 of 64
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    Conference paperPublicationMetadata only
    COSMOS on steroids: a Cheap detector for cheapfakes
    (The ACM Digital Library, 2021) Akgül, T.; Civelek, Tuğçe Erkılıç; Uğur, Deniz; Beğen, Ali Cengiz; Computer Science; BEĞEN, Ali Cengiz; Civelek, Tuğçe Erkılıç; Uğur, Deniz
    The growing prevalence of visual disinformation has become an important problem to solve nowadays. Cheapfake is a new term used for the altered media generated by non-AI techniques. In their recent COSMOS work, the authors developed a self-supervised training strategy that detected whether different captions for a given image were out-of-context, meaning that even though pointing to the same object(s) in the image, the captions implied different meanings. In this paper, we propose four methods to improve the detection accuracy of COSMOS. These methods range from differential sensing and fake-or-fact checking that detect contradicting or fake captions to object-caption matching and threshold adjustment that modify the baseline algorithm for improved accuracy.
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    ArticlePublicationMetadata only
    A survey on bitrate adaptation schemes for streaming media over HTTP
    (IEEE, 2019) Bentaleb, A.; Taani, B.; Beğen, Ali Cengiz; Timmerer, C.; Zimmermann, R.; Computer Science; BEĞEN, Ali Cengiz
    In this survey, we present state-of-the-art bitrate adaptation algorithms for HTTP adaptive streaming (HAS). As a key distinction from other streaming approaches, the bitrate adaptation algorithms in HAS are chiefly executed at each client, i.e., in a distributed manner. The objective of these algorithms is to ensure a high quality of experience (QoE) for viewers in the presence of bandwidth fluctuations due to factors like signal strength, network congestion, network reconvergence events, etc. While such fluctuations are common in public Internet, they can also occur in home networksor even managed networks where there is often admission control and QoS tools. Bitrate adaptation algorithms may take factors like bandwidth estimations, playback buffer fullness, device features, viewer preferences, and content features into account, albeit with different weights. Since the viewer's QoE needs to be determined in real-time during playback, objective metrics are generally used including number of buffer stalls, duration of startup delay, frequency and amount of quality oscillations, and video instability. By design, the standards for HAS do not mandate any particular adaptation algorithm, leaving it to system builders to innovate and implement their own method. This survey provides an overview of the different methods proposed over the last several years.
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    Consumer communications and the next generation broadcast networks
    (IEEE, 2016) Beğen, Ali Cengiz; Kolberg, M.; Merabti, M.; Computer Science; BEĞEN, Ali Cengiz
    Over 20 years ago the challenge for the communications community was the convergence between networking, telecommunication, and broadcasting. This challenge has been fairly well met, and we now note that around the world telco companies are being re-born as new hybrid telco-broadcast entities, and the reverse is true for many broadcasting corporations that provide Internet services in addition to their core business. Current and new infrastructure networks now face a number of major challenges that include increasing efficiency in the delivery of services from the installed or legacy systems, and an evolution path to address more topical concerns such as energy conservation and the increased heterogeneity in media, applications, and delivery systems. Central to all of these are the ever changing consumer communication habits and demands. These particular themes are addressed in this issue.
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    Automated objective and subjective evaluation of HTTP adaptive streaming systems
    (IEEE, 2018-06-26) Timmerer, C.; Zabrovskiy, A.; Beğen, Ali Cengiz; Computer Science; BEĞEN, Ali Cengiz
    Streaming audio and video content currently accounts for the majority of the internet traffic and is typically deployed over the top of the existing infrastructure. We are facing the challenge of a plethora of media players and adaptation algorithms showing different behavior but lack a common framework for both objective and subjective evaluation of such systems. This paper aims to close this gap by (i) proposing such a framework, (ii) describing its architecture, (iii) providing an example evaluation, (iv) and discussing open issues.
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    Conference paperPublicationOpen Access
    Common media server data (CMSD) - update on implementations and validation of key use cases
    (ACM, 2023-06-16) Pham, S.; Law, W.; Beğen, Ali Cengiz; Silhavy, D.; Berthelot, B.; Arbanowski, S.; Steglich, S.; Computer Science; BEĞEN, Ali Cengiz
    The CTA-5006 (Common Media Server Data, CMSD) specification establishes a uniform method for media servers to exchange data with each media object response. The aim is to enhance distribution efficiency, performance, and ultimately, the user experience. We provide an overview of CMSD implementations and focus on integrating CMSD into the dash.js reference player. Three use cases are evaluated to demonstrate the advantages of CMSD, including leveraging edge server throughput estimates to improve initial bitrate selection and low-latency live streaming, prefetching manifests and segments to improve startup delay, and allowing an edge server to suggest a playback bitrate to improve the collective experience. The outcomes from the initial implementations confirm the benefits of using CMSD.
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    EditorialPublicationOpen Access
    Foreword
    (The ACM Digital Library, 2020-05) Toni, L.; Beğen, Ali Cengiz; Alay, O.; Timmerer, C.; Computer Science; BEĞEN, Ali Cengiz
    N/A
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    Conference paperPublicationOpen Access
    Common media client data (CMCD): Initial findings
    (Association for Computing Machinery, Inc, 2021-07-16) Bentaleb, A.; Lim, M.; Akçay, Mehmet Necmettin; Beğen, Ali Cengiz; Zimmermann, R.; Computer Science; BEĞEN, Ali Cengiz; Akçay, Mehmet Necmettin
    In September 2020, the Consumer Technology Association (CTA) published the CTA-5004: Common Media Client Data (CMCD) specification. Using this specification, a media client can convey certain information to the content delivery network servers with object requests. This information is useful in log association/analysis, quality of service/experience monitoring and delivery enhancements. This paper is the first step toward investigating the feasibility of CMCD in addressing one of the most common problems in the streaming domain: efficient use of shared bandwidth by multiple clients. To that effect, we implemented CMCD functions on an HTTP server and built a proof-of-concept system with CMCD-Aware dash.js clients. We show that even a basic bandwidth allocation scheme enabled by CMCD reduces rebuffering rate and duration without noticeably sacrificing the video quality.
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    Conference paperPublicationOpen Access
    Bandwidth prediction in low-latency media transport
    (ACM, 2023-06-16) Bentaleb, A.; Akçay, Mehmet Necmettin; Lim, M.; Beğen, Ali Cengiz; Zimmermann, R.; Computer Science; BEĞEN, Ali Cengiz; Akçay, Mehmet Necmettin
    Designing a robust bandwidth prediction algorithm for low-latency media transport that can quickly adapt to varying network conditions is challenging. In this paper, we present the working principles of a hybrid bandwidth predictor (termed BoB, Bang-on-Bandwidth) we developed recently for real-time communications and discuss its use with the new Media-over-QUIC (MOQ) protocol proposals.
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    EditorialPublicationMetadata only
    Foreword
    (ACM, 2021) Alay, O.; Hsu, C.-H.; Beğen, Ali Cengiz; Computer Science; BEĞEN, Ali Cengiz
    N/A
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    Are the streamingformat wars over?
    (IEEE, 2018-11-28) Beğen, Ali Cengiz; Syed, Y.; Computer Science; BEĞEN, Ali Cengiz
    An average US viewer watches some form of video content five hours a day. The majority ofthe viewed content is still broadcast (over the air, cable, IPTV or satellite), however, the share of the streaming content has been on the rise. In the past year, we witnessed some much needed convergence in the standards and the industry, and as a result of this, the forecast forstreaming services looks more promising than ever.